Installations for reprocessing irradiated nuclear fuels have what are referred to as "large-area hot cells" for accommodating the process equipment. In such radiation-shielded cells, the process components are set up in frames or support structures known as racks.
Routine maintenance and repair operations on the process components within the large-area cell, which is charged with radioactive radiation, are to be carried out without the need for operating personnel to enter the cell. It has therefore been proposed that the operations should be carried out by means of movable remote-handling machines. Accordingly, the racks carrying the process equipment are set up in such a way as to be consistent with remote handling, namely, along the longitudinal walls of the hot cell in two mutually adjacent rows.
This arrangement leaves free a central passageway in which transportable remote-handling machines for routine maintenance, repair and for replacing individual process components or fully equipped racks can be moved. A combination of remote-handling machines has already been proposed for routine maintenance operations and for the replacement of individual process components or entire racks. In this connection, one proposal provides that a remotely-controlled travelling bridge crane operates under the roof above the racks, the crane passing over the two rows of racks and the central passageway. After all connections and conduits have been released, the bridge crane is used to lift the racks or heavy individual components out of their anchoring, and move them horizontally into the transportation passageway.
In addition to the above-mentioned travelling bridge crane, a manipulator carrier system was provided, with horizontal operation from the middle passageway to the process components for positioning operating and maintenance apparatus and tools. The manipulator carrier system affords the possibility of using electrical servo and power manipulators. Small components are manipulated with the available manipulators and lifting appliances, in dependence on the configurations of the manipulator carrier system.
A proposed manipulator carrier system is configured as a crane-like arrangement wherein a vertical column is arranged on a bridge carrier movable along the large-area cell. The vertical column is movable on a trolley of the bridge carrier. Disposed on the column is a vertically movable chassis frame having a cantilever arm which has a tool carrier plate for mounting or connecting the tools or handling equipment. This proposed manipulator carrier system is arranged to be movable under remote control along the large-area cell beneath the bridge crane and in a separate plane.
An advantageous division of work can be achieved with the arrangement of a travelling bridge crane and a manipulator carrier system. The remotely-controlled bridge crane is used predominantly for carrying and transporting conduit connections, components and individual racks. It performs the operations of lowering and holding tools such as cutting and welding equipment as required. The manipulator carrier system which is movable in the transportation passageway is provided for guiding impact wrenches or other special tools which can be utilized as additional dismantling aids. The manipulator carrier system can also be used for carrying television equipment or other ancillary devices.
In an effort to further improve the known remote-handling procedures, investigations are made into and efforts directed to carrying out handling and operating steps in a more precise and simpler fashion. The hitherto conventional mode of operation is to be simplified and speeded up, for at least some of the transportation, handling and operating steps. In addition, the effort is made to increase the operational possibilities of the remote-handling techniques.